Different Red Dot Footprints & Mounting Compatibility Explained

Red dot sights are a crucial accessory for many firearms. They come with different mounting standards, which are commonly referred to as “footprints.” These mounting standards have unique characteristics, allowing swift and snug attachment to a compatible firearm. There are numerous footprints, and finding one that is compatible with your firearm’s mounting surface is vital for the secure and correct operation of the sight on the firearm. In this article, we cover the four most commonly used red dot sight footprints as well as what you can do when your footprint is not compatible with your firearm.

What Is A Red Dot Footprint?

A red dot sight footprint refers to the mounting standard and the entire bottom surface of a red dot sight. Common characteristics of a red dot footprint include the pattern of the screw holes and the recesses on the underside of the red dot sights corresponding to the firearm’s mounting system or adapter plate.

What Is The Mounting Surface For A Red Dot?

The mounting surface for a red and green dot sight is the surface of the firearm on which red dots are mounted or attached. It is usually located on the top of a firearm’s slide for handguns and the top rail for rifles.

The location and type of mounting surface can affect factors such as height, eye relief, and aiming. Therefore, it is important to consider these aspects when choosing and mounting a red dot sight.

4 Types of Red Dot Footprints

There are a lot of red dot sight footprints on the market. Below we discuss the four most commonly used footprints for red dot sights.

1. Docter/ Noblex Standard
2. Trijicon RMR
3. Leupold Deltapoint Pro
4. Aimpoint Micro

1. Docter/ Noblex Standard

The first red dot sight footprint is the Docter (now Noblex) footprint. The Docter footprint has four sockets on the underside of the sight that fits perfectly into the pins in the mount or slide, with two screws that are 19mm apart, providing retention. This footprint is the most common red dot footprint and is similar to RMSC footprint optics that are used by most of the popular red dot sights, such as Trijicon, Holosun, and Vortex.

Compatible red dot sights include:

• Noblex/Docter Quick Sight, Sight C, Sight II+, Sight III
• Vortex Viper
• Burris Fastfire II and III
• Meopta Meosight III

2. Trijicon RMR

The Trijicon RMR mounting standard uses two screw holes placed 40mm apart and have two sockets for the mounting pins. This footprint is especially popular among micro-small tube sights or small tube sight. I’ve rated any of the best optics with rmr footprint and they are top quality.

Compatible red dot sight include:

• Trijicon RMR and SRO
• Holosun 407C, 507C, 508T
• C&H Precision Weapon Systems V4 MIL / LEO MOS plates

3. Leupold Deltapoint Pro

Made by the esteemed Leupold, this footprint is proprietary to Leupold-manufactured red dot sights. It has four locating pins and uses two screws to secure the mounting.

Compatible red dot sights include:

• Leupold Deltapoint Pro
• Holosun 407K and 507K (these Holosun red dots are narrower and have a modification to the standard Deltapoint Pro footprint)

4. Aimpoint Micro

The Aimpoint Micro footprint is one of the most widely adopted footprints, especially for use on small tube sights. The footprint has four screw holes, and the surface of the mounting surface is slightly lifted in the middle.

Compatible red dot sights include:

• Aimpoint Micro H-1, H-2, T-1, T-2, CompM5
• Sig Sauer Romeo 4, 5 (certain models)
• Vortex Crossfire Red Dot, SPARC AR, SPARC II
• Holosun HS403, HS503, HS515 series

How To Get Your Pistol Slide Milled To Match Your Preferred Optic

Usually, a pistol will come as “optics ready,” meaning it has already been milled and ready for red dot sight plates and mounting. However, when it doesn’t come as optics ready, or you want it milled to have the same mounting standard and same footprint as your preferred optic, then you can follow these steps:

1. Optic Selection – First, select the optic or red dot sight you want to use. The specific optic will determine the footprint and, consequently, the specifics of the milling process.
2. Choose A Gunsmith – Next, you have to choose a reputable gunsmith or company that offers slide milling services specifically for red dot optics. I like using Wheaton Arms, C&H Precision Weapons and Modern Samurai Project. If you want to do the milling process yourself, then you can follow our guide.
3. Milling Process – The gunsmith will most likely use a CNC (computer numeric control) machine to cut a recess in the top of the pistol slide that matches the footprint of your chosen optic. The gunsmith acts with extreme precision, as it is crucial that the depth and pattern of the cut match the specifications of the optic exactly in order to ensure a snug fit.
4. Finishing – After the milling process is finished, the slide needs to be refinished to prevent corrosion. Typical finish methods include bluing, parkerizing or simply applying a surface finish such as Cerakote.
5. Mounting – Finally, your pistol is ready to be mounted with your optic. However, it is important that you follow the correct procedure when mounting your pistol, such as applying the right amount of torque and using the correct screws.
6. Sight In – After you mount your pistol, you will need to sight in / zero it. Here is a guide on sighting in your red dot sight the right way.

Frequently Asked Questions

The Bottom Line

There are various red dot footprints available, and understanding their mounting compatibility is fundamental for anyone looking to enhance their firearm with a red dot sight. Remember, each footprint has its unique features, such as varying amounts of screw holes and at different distances apart from each other. Always verify the compatibility between your firearm and red dot sight, possibly requiring an adapter plate. Ultimately, when you follow these guidelines, you can choose a sight that will work seamlessly with your firearm – contributing to a more enjoyable and accurate shooting experience.